1. Field of the Invention
The present invention relates to an image-forming apparatus such as a printer, photocopier, a facsimile machine, and the like, a storage medium, and a computer system.
2. Description of the Related Art
As one type of an image-forming apparatus, there is known an apparatus comprising a rotary-type developing unit, in which the rotary-type developing unit comprises a plurality of developing devices arranged radially about its axis of circular movement. The developing devices develop a latent image formed on a photoconductor using different-colored toner contained therein. When an image signal is transmitted from an external device such as a host computer, this image-forming apparatus sequentially changes the developing devices by rotating the rotating shaft, to thereby locate one of the plurality of developing devices in a developing position opposing the photoconductor. A toner image is formed by developing the latent image formed on the photoconductor, and the image is transferred to an intermediate medium. A color image is formed by superimposing the plurality of toner images, by sequentially changing the plurality of developing devices and repeating the developing and transferring in a similar manner.
Further, since each of the developing devices is attached in a respectively detachable manner, some developing devices comprise a detector which detects whether or not each of the developing devices is attached.
However, in an image-forming apparatus having a plurality of developing devices, the components must be relatively moved so as to sequentially move a certain developing device to a developing position opposing the photoconductor. Therefore, it is difficult to make it always possible to detect whether or not each of the developing devices is attached. For this reason, the above-mentioned detector is constructed so that it can detect whether or not each of the developing devices is attached, only when the respective developing devices and the image-forming apparatus body are arranged to be in a predetermined position.
Therefore, there is a problem in that, upon, for example, turning the power of the apparatus ON or exchanging a developing device, it is not possible to identify whether or not each of the developing devices is attached, and the presence/absence of attachment of each of the developing devices has to be confirmed by the above-mentioned detector.
Further, there are other types of an image-forming apparatus, other than the apparatus comprising the rotary-type developing unit that comprises a plurality of developing devices, which develop a latent image formed on a photoconductor using the different-colored toner contained therein, arranged radially about its axis of circular movement. There is known an apparatus comprising a slide-type developing unit 201, as shown in FIG. 14, in which the developing devices 200 are arranged in parallel. When an image signal is transmitted from an external device such as a host computer, these image-forming apparatuses locate one of the plurality of developing devices in a developing position opposing the photoconductor 20, by sequentially changing the developing devices through rotation of the rotating shaft in case of a rotary-type developing unit, and by sliding the developing devices 200, arranged in parallel, in case of a slide-type developing unit 201. A toner image is formed by developing the latent image formed on the photoconductor, and the image is transferred to an intermediate medium. A color image is formed by superimposing the plurality of toner images, by sequentially changing the plurality of developing devices and repeating the developing and transferring in a similar manner.
Developing devices corresponding to each of the above-mentioned colors are attached so that they can be respectively detached. However, the position of attachment to the developing unit is determined according to the color of the toner contained therein; and therefore, a developing device having the correct color must be attached to that attachment position. Therefore, a storage element storing therein information corresponding to each developing device, such as information relating to the color of the toner contained therein, is attached to each developing device; and, for example, upon turning the power of the apparatus ON or exchanging a developing device, confirmation is made by reading the data in the storage element using reading means provided on the body of the image-forming apparatus.
However, in such an image-forming apparatus, the components must be relatively moved so as to sequentially move a developing device having a certain color to a developing position opposing the photoconductor. Therefore, in a state where each of the developing devices and the image-forming apparatus are maintained connected, it is difficult to confirm, at all times, whether or not the developing devices being attached to the developing unit are the correct developing devices. Therefore, there is a problem in that, for example, upon exchanging of a developing device, even if another developing device having an inappropriate color is attached after a developing device has been detached, such a circumstance cannot be detected; and if printing is carried out in this state, a defective image with colors completely different from those of the image data will be output, thereby causing unwanted consumption of expendables such as ink, paper, and the like.
Further, some of the developing devices used in the above-mentioned image-forming apparatus comprise storage means capable of recording thereon various kinds of information, such as information relating to color of the toner contained in that developing device, consumption amount of the toner, and the like. The storage means is electrically connected with the body of the image-forming apparatus through mutual contact of the developing device and reading means provided on the body of the image-forming apparatus for reading the information from the developing device; and accordingly, the information is read. This information is used for various purposes.
No problem arises when power is being continuously supplied to the image-forming apparatus in a state where the above-mentioned developing device and the above-mentioned reading means are placed in contact. However, assume a case where, for example, in a state where the developing device and the reading means are in contact with each other, the power supply to the image-forming apparatus is stopped, such as when a user erroneously turns the image-forming apparatus OFF, and then the power supply to the image-forming apparatus is restarted, such as when the user turns the image-forming apparatus ON again. In such a case, because of interruption in power supply, the image-forming apparatus will not record, or remember, that the developing device and the reading means were in contact with each other; and therefore, the image-forming apparatus may carry out an operation to move the developing unit, that is for example, to move the developing unit to a later-explained home position. As a result, there arises a problem in that, since the developing devices attached to the developing unit will also move according to the movement of the developing unit, the contacting sections of the mutually-contacting developing device and the reading means may be damaged.
Further, there arises a problem that disorders will be caused in image-forming operations, for reasons such as that the movement of the developing device is interrupted, the movement of the developing unit towards its home position, which is to be a reference position of rotation of the developing unit, is interrupted, and the like.